Lamp glass envelope and method for manufacture a lamp glass envelope

ABSTRACT

A method for producing the type lamp glass envelope used in a reflector lamp is disclosed which employs a ribbon machine. Said ribbon formed lamp glass envelope includes a cylindrical neck portion terminating at one end in a curved reflector portion closed by an integral flattened face portion of lesser curvature with light distributing elements being formed on the exterior surface of said face portion. In its preferred embodiments, the reflector portion of said lamp glass envelope is of the PAR type which can further include truncation of the parabolic shape with opposing substantially flattened parallel surfaces as well as face portions for said lamp glass envelope which can be circular or rectangular in shape. A novel mold construction permitting said lamp glass envelope to be blown on a ribbon machine includes a pair of cooperating halves to form the sides of the curved glass envelope in a central cavity and which terminate at the ends of said cavity in a separate curved or flat base part which undergoes reciprocal motion in a vertical direction during said manufacturing process.

This is a division of application Ser. No. 519,437 filed Aug. 1, 1983.

CROSS-REFERENCE TO RELATED APPLICATION

My U.S. patent application Ser. No. 519,436 (LD 9101), filedconcurrently herewith, for "Ribbon Blown Glass Article" and assigned tothe assignee of the present invention, pertains to a glass envelopeformed on a ribbon machine so that it terminates in a non-spherical orflat base.

BACKGROUND OF THE INVENTION

This invention relates to forming the lamp glass envelope for reflectortype lamps on a ribbon machine wherein a novel mold construction isemployed having three basic parts which cooperate in forming a bulbshape of generally parabolic contour and which terminates in a flattenedface portion having light distributing elements formed on the exteriorsurface thereof.

The lamp glass envelopes customarily employed for reflector lamps suchas PAR lamps and automotive headlamps are now formed by pressingseparate reflector and lens parts in glass molds requiring not onlyrelatively thick cross-sections for each part but further require thatthese parts by fusion sealed together during the lamp manufacture. Lightdistributing elements are located on the inner surface of theconventional lens members to shape the beam pattern of light emergingfrom the reflector surface which further requires an accurateregistration with the conventional reflector members to do soeffectively. A serious problem has long been recognized with saidconventional pressed lamp constructions arising from the lack of properregistration when these separate lens and reflector members are fusionsealed together.

Accordingly, an important object of the present invention is to providea lamp glass envelope for a reflector lamp having a unitary integralconstruction which includes the reflector and lens portions when saidlamp glass envelope is initially formed.

Another important object of the present invention is to reduce theamount of glass customarily employed in the lamp glass envelope of areflector lamp as well as significantly reduce the difficulties nowencountered with lack of proper alignment between the lens and reflectorportions in pressed type lamp constructions.

Still a further important object of the present invention is to providean improved method for manufacture of said novel unitary lamp glassenvelope on a ribbon machine by means of a novel mold design.

SUMMARY OF THE INVENTION

In accordance with the present invention, the novel ribbon formed lampglass envelope for a reflector type lamp includes a cylindrical neckportion terminating at one end in a curved reflector portion closed byan integral flattened face portion of lesser curvature with lightdistributing elements being formed in the exterior surface of said faceportion. Said lamp glass envelope can be formed with hard or soft glassand with the light distributing elements formed on the exterior surfaceof the face portion including lenticular as well as prism shapedprotuberances. In one preferred embodiment, a PAR type lamp glassenvelope is blowm from a molten hard glass composition wherein acylindrical neck portion terminates in a parabolic shaped reflectorportion closed by a flattened face portion of lesser curvature withlenticular shaped elements being formed on the exterior surface of saidface portion and with said face portion being circular in shape. In adifferent preferred embodiment, an automotive type lamp glass envelopeis formed on a ribbon machine with a molten soft glass compositionwherein the parabolic reflector portion of said envelope is truncated atopposite sides by substantially flat and parallel surfaces and with thebase part being rectangular in shape and provided with lightdistributing elements on the exterior surface thereof having a prismelement pattern of already known configuration.

The basic method of the present invention continuously forms the blownglass envelope from a molten ribbon of glass supported on a movingconveyor which includes the steps of:

(a) blowing a portion of the glass from said molten ribbon into thecentral cavity of a multi-part mold, said mold including a pair ofcooperative halves forming the curved reflector portion of said blownglass envelope by encircling the molten glass while being blown andwhich mold halves further contain a separate base part at the lower endof said cavity forming a flattened face of lesser curvature in saidblown glass envelope with light distributing elements being formed onthe exterior surface,

(b) said base part being provided with reciprocal motion in a verticaldirection,

(c) having these base parts of said mold move upwardly and remain in anupward position while the glass envelope is being blown but then movedownwardly and release the face of the solidified blown glass envelopebefore the mold halves are opened,

(d) opening the mold halves to release the sides of the solidified blownglass envelope, and

(e) severing the blown glass envelope from the moving glass ribbon.

In a preferred form of said method for manufacture of the abovedescribed PAR type lamp glass envelope, the mold halves include means toform a steam cushion against which the glass envelope is blown, such asthe already known ventilated paste type mold and with said mold halvesbeing rotated during formation of the envelope. In forming the abovedescribed truncated automotive lamp embodiment according to the presentmethod, however, the mold halves are understandably not rotated when theenvelope is being formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a fragmentary side elevation view of an exemplaryglass ribbon machine embodying the present invention.

FIG. 2 is a perspective view illustrating a simplified mold designaccording to the present invention.

FIG. 3 is a perspective view illustrating one type lamp glass envelopeformed according to the present invention.

FIG. 4 is a perspective view illustrating a different lamp glassenvelope formed according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, there is partially depicted a conventional hotribbon machine 10 which forms the presently improved lamp glass envelope12 from a molten ribbon of glass 14 that is being carried on a movingconveyor having interconnected orifice plates 16. The molten glass isblown downwardly by blowheads 18 into the central cavity portions ofglass molds 20 constructed in accordance with the present invention. Themold halves 22 are closed while the lamp glass envelope is being blownwhile the separate base portion 24 of said molds is moved upwardly andretained in the upward position during this step in the manufacturingprocess. Downward movement of said base part in the molds isautomatically carried out on said ribbon machine by conventional meansafter the molten glass is solidified in the mold cavities as a necessarystep before said mold halves are opened. Rotation of the mold halves 22which can be carried out when the glass envelopes are formed in thismanner as well as severing the blown glass envelopes from the movingglass ribbon after the mold halves have been opened are all carried outin the customary manner now being utilized in ribbon machinemanufacture.

A simplified mold construction 26 incorporating the essential structuralfeatures required to form the above described lamp envelope embodimentis depicted in FIG. 2. Specifically, a pair of mold halves 28 and 30cooperate to form the reflector sides of the curved blown glass envelopein a central cavity 32 which terminates in a separate curved base part34 providing a lesser degree of curvature to the face portion of saidglass envelope than its reflector sides. There is included a pattern oflight distributing elements 36 on the upper surface of said curved basepart forming the previously mentioned proturbances on the exteriorsurface of said lamp glass envelope. Said base part 34 is also providedwith reciprocal motion in the vertical direction by means of beingmounted on a bearing surface 38 and with said upward motion beinglimited by physical contact with a rim surface 40 machined at the lowerend of the cooperating mold halves. In said type mold construction, thecooperating mold halves can be rotated in the customary manner to form asymmetrical lamp glass envelope having sides with a parabolic contour,said mold halves being further provided with ventilated openings 42along with a paste coating 44 being applied to the inner surface of thecentral mold cavity. On the other hand, the cooperating surface of basepart 34 is devoid of a paste coating but is provided with vent openings47 to help relieve steam from the mold cavity and produce a more sharplydefined pattern in the light distributing elements formed by saidsurface.

In FIG. 3 there is depicted a perspective view of a typical PAR typelamp glass envelope according to the present invention. Said ribbonformed lamp glass envelope 46 for a reflector type lamp includes acylindrical neck portion 48 terminating at one end in a curved reflectorportion 50 closed by an integral flattened face portion 52 of lessercurvature having light distributing elements 54 formed on the exteriorsurface of said face portion. As can be observed, a conventionalaluminized reflective coating 56 has been deposited on the inner surfaceof said curved reflector portion 50 to provide desired light reflectionfrom said reflecting surface. This type lamp glass envelope iscustomarily formed with a conventional hard glass composition and withsaid flattened face portion 52 having a circular contour 58. The lightdistributing elements 54 formed on the exterior surface of the faceportion in said lamp glass envelope can also comprise the conventionalpattern of lenticule shaped elements now used to shape the light beampattern emerging from this type lamp construction. Lamp glass envelopesof this type have been found not only to afford a substantial reductionin glass weight but far greater dimensional control with respect to alldimensions as compared with PAR lamps having a pressed glassconstruction.

FIG. 4 is a perspective view of a truncated reflector lamp glassenvelope 60 having a generally parabolic reflecting surface 62 which istruncated on opposite sides 64 and 66 by substantially flat and parallelplanar surfaces. Said reflecting surface 62 represents an approximatelyhalf section or slightly wider portion of a symetrical parabolicreflector which can provide a desired beam control of the reflectedlight beam pattern emerging from said type lamp construction. Forexample, said truncated reflector design can be used to eliminateundesirable glare which can otherwise emerge if said lamp is employedfor headlight vehicle illumination. Said lamp glass envelope furtherincludes a cylindrical neck portion 70 terminating in said truncatedreflector portion 62 which is again closed by an integral flattened faceportion of planar contour 72 having light distributing elements 74formed on the exterior surface of said face portion. Said type lampglass envelope can be formed with a conventional soft glass compositionwith the light distributing elements 74 utilizing a customary pattern ofprism elements. Base part 72 is rectangular in shape in accordance withthe style of headlamps now being used in automotive vehicles. The sametype and extent of improvements noted above in connection with thepreviously described lamp embodiment can be expected for truncatedreflector lamps made in accordance with the present invention. As can beobserved from the drawing, however, a visible mold seam 76 is producedin the present lamp embodiment due to non-rotation of the mold halveswhen the glass envelope is being blown.

While preferred embodiments of the present invention along with improvedmethods for manufacturing said embodiments have been shown anddescribed, various other embodiments along with modifications in thedescribed method of manufacture will become apparent to persons skilledin the art without departing from the spirit and scope of the presentinvention. For example, a mold construction for use in forming the abovedescribed FIG. 4 lamp envelope embodiment does not require a pastecoating and vent openings since the mold halves are not rotated.Additionally, the base part of the mold is permitted to rotate slightlyin mold designs according to the present invention wherein the moldhalves rotate and which avoids distorting the light distributing patternon the face of the lamp glass envelope while the glass is still molten.The scope of the present invention is thereby limited only to thefollowing claims.

I claim:
 1. A method of continuously forming a blown glass envelope fora reflector type lamp from a molten ribbon of glass supported on amoving conveyor which comprises:(a) blowing a portion of the glass fromsaid molten ribbon into the central cavity of a single multi-part mold,said mold including a pair of cooperative halves forming the curvedreflector portion of said blown glass envelope by encircling the moltenglass while being blown and which mold further includes a separate basepart located at the lower end of said cavity forming a flattened face oflesser curvature in said blown glass envelope having light distributingelements on the exterior surface, (b) said base part being provided withreciprocal motion in a vertical direction, (c) having the base part ofsaid mold move upwardly and remain in an upward position while the glassenvelope is being blown to form all structural features in said glassenvelope but then move downwardly and release the face of the solidifiedblown glass envelope before the mold halves are opened, (d) opening themold halves to release the sides of the solidified blown glass envelope,and (e) severing the blown glass envelope from the moving glass ribbon.2. A method as in claim 1 wherein the mold halves include means to forma steam cushion against which the glass envelope is blown while saidmold halves are rotating.
 3. A method as in claim 2 wherein thereflector portion of the blown glass envelope is parabolic in shapewhile the face portion of said blown glass envelope is circular in shapewith the light distributing elements formed on the exterior surfacebeing lenticular in shape.
 4. A method as in claim 3 using hard glass.5. A method as in claim 1 wherein the mold halves do not rotate and theface portion of said blown glass envelope is rectangular in shape withthe light distributing elements formed on the exterior surface beingprism shaped.
 6. A method as in claim 5 using soft glass.